CRYSTALLOGRAPHY OF COMPOUNDS OF CALIFORNIUM .2. CRYSTAL STRUCTURE AND LATTICE PARAMETERS OF CALIFORNIUM OXYCHLORIDE AND CALIFORNIUM SESQUIOXIDE

Californium oxychloride has been found to exhibit the tetragonal PbFCl-type structure. X-ray diffraction data from three polycrystalline samples give the average lattice parameters a = 3·956±0·002 A and c = 6·662±0·009 A, where the error limits represent the 95 per cent confidence interval. Three samples of a low-temperature californium sesquioxide have been prepared. Two of these samples, prepared by the hydrolysis of other californium compounds, were found to exhibit the cubic, Mn2O3-type structure with the average lattice parameter a = 10·838±0·020 A. The third sample, reacted in oxygen, had the lattice parameter a = 10·809±0·003 A, where the error limits represent the 95 per cent confidence level and reflect the internal consistency of the data for that particular sample. In an earlier study [1], the lattice parameter of an air-ignited oxide sample was 10·811±0·005 A; upon treatment with H2(g) the lattice parameter increased by 0·49 per cent. These changes in the lattice parameter may reflect small departures from the sesquioxide stoichiometry and thus may constitute evidence for higher and/or lower oxidation states of californium. © 1969.